Eric Mahmoud strides through the halls of a once-vacant north Minneapolis nursing home he converted 20 years ago into a beehive of educational reform. He greets the uniformed Harvest Preparatory Academy children with a "What's up, scholars?"

Two girls, grinning under head scarves, come zipping around the corner. Mahmoud asks them to stop, go back to the end of the hall and try again. They cross their arms, adhering to one of the strict charter school's many rules, and slowly retrace their steps.

"Super job, scholars," Mahmoud says, towering over them at 6-foot-3 in a crisp charcoal suit. "That's a much better job, and I'd like to thank you for being quiet in the hallways."

After all, kids are taking their Minnesota Comprehensive Assessment tests down the hall and, at Harvest Prep, MCAs are akin to a holy grail.

With 100-minute time blocks devoted every day to drilling on math tables and reading, the students -- nearly all black and poor -- aced the standards tests last year. They outperformed statewide averages and Minnesota's white students, vaulting Mahmoud to rock-star status among education reformers.

"Eric has forever reshaped the conversation about low-income children of color and what's possible on the North Side," said Kim Nelson, an executive at General Mills, one of the big-name companies lining up behind Mahmoud as he obliterates an achievement gap that for years has ranked Minnesota's black boys far below their white counterparts in everything from third-grade math to graduation rates.

The Minneapolis School District, which for years viewed Mahmoud as a competitor siphoning off the North Side's best and brightest, now embraces his efforts. The school board recently authorized him to replicate his success at a new school this summer, and as many as three more schools over the next 10 years.

If all goes through, Mahmoud's reach will more than double to 2,500 kids from the nearly 1,000 students currently enrolled at Harvest Prep, which is really five schools folded into one building, from preschool to eighth grade.

"He has shown a commitment and tenacity, and if there is something, indeed, that is attracting families to Harvest, why wouldn't we be replicating it in other schools?" Minneapolis Superintendent Bernadeia Johnson said. "There's not this braggadocio 'look at what I'm doing' with Eric - he has just been humbly and quietly working away, trying to change outcomes for students."

A former engineer from a gritty Philadelphia neighborhood, Mahmoud admits his path hasn't always been rosy. He's overcome intestinal cancer, financial setbacks, foreclosures on three residential properties and an ill-fated attempt to run a school bus business.

"I haven't always been the smartest or the strongest, but I was the most persistent," he said recently while driving to St. Cloud to present his strategies to the school board.

Harvesting Purple Rain

The oldest of four children, Mahmoud, 51, grew up as Eric McLaughlin Jr. He changed his name in 1984 when he converted to Islam, but retained a work ethic passed down from parents who worked as a carpenter and a Sears sales manager.

In high school, he was more worried about getting home from school alive than academics. He nevertheless graduated second in his class, earning a full-ride scholarship to the University of Wisconsin.

As a Madison freshman in 1979, he attended a Student Union rally sponsored by the International Committee Against Racism, featuring former Black Panther Stokely Carmichael. That's where he met and fell in love with Ella, his wife and school co-founder.

It was Ella who led Eric into education, with her dream of opening a child-care center in her hometown of Minneapolis. But first Mahmoud put his engineering degree to work making laser gyros at Honeywell, pacemakers at Medtronic and matrix dot printer heads for Juno Enterprises. He's taken those skills to schools.

"Smart students come off the end of the line now, but we have quality control checks all along the line," he said. "You can't wait until the end of the line to address particular problems, so we're constantly checking and assessing."

Louis King, a former Minneapolis School Board member who runs the Summit Academy adult job-training center across Olson Memorial Highway from Harvest Prep, has known Mahmoud for 20 years and has a 10-year-old daughter, Lauryn, in his fifth grade.

"We're seeing an engineer at work," King said. "That's how his DNA is wired and he realizes you can't turn out a faulty product in this line of work because there will be no recalls."

SEED (Success in Educational Evolutionary Development) was the Mahmouds' first preschool program, operated out of their home with 10 kids, including three of their own, whom they adopted as toddlers from a nearby housing project. Parents urged them to start a school, and their yin-yang partnership worked well.

"I'm the fluff person who likes hugging children and Eric is the engineer, the structured strategic thinker and visionary," said Ella, who has a doctorate but says she's glad to work in the background as the school's human resources director.

Their big break came when rock star Prince heard about their new Harvest Prep school 20 years ago and invited them to Paisley Park. Ella said the musician remained behind a glass wall while they made their pitch to his aides. The next day, Prince's people called and said he would contribute $200,000.

"I fainted and hung up on her," Ella said. "It put us in a whole other dimension."

In 2005, Mahmoud was visiting his mother in Philly when he became ill with "explosive diarrhea." He wound up hospitalized with a ruptured appendix. During surgery, doctors detected a cancerous tumor on his small intestines. If his appendix hadn't burst, the cancer would probably have spread to his liver and killed him.

"Lying in bed, I realized life is too short and I had to stop playing with this thing and do something really great," Mahmoud said.

Harvest Prep, he said, "was the best of the worst" at the time. He could brag about being the best school in north Minneapolis, but from his hospital bed, he decided to make the school "not just a good institution, but a great one."

With longer days, from 8 a.m. to 4:45 p.m., and longer school years, Harvest Prep students spend about 35 percent more time in school than traditional schools. The drilling is rigid, the culture disciplined. For example, Mahmoud talks about a new way to get children fully invested and behaving through an elaborate point system.

Each Monday, students are given 40 points and they gain or lose more based on their behavior throughout the week. Friday, they receive a "paycheck," a computer printout of the week's point tally. If they have more than 45 points, they head to the Fun Friday Room where a pizza and ice cream party is rocking. Students with less than 40 points are sent to the Bench - a study hall with the strictest teacher where sounds of joy can be clearly heard from the Fun Friday Room.

In five weeks, the number of students on the Bench dropped 50 percent and one problematic youngster actually broke out crying when he finally made it to the Fun Friday Room.

According to recent tax documents, Harvest Prep is a $4 million nonprofit with 100 employees. Mahmoud earned $163,000 in base salary. That's less than the Minneapolis superintendent's $190,000 base salary and more than Bill Wilson's $146,000 salary as director of a similar charter, St. Paul's Higher Ground Academy.

Many backers, few detractors

Mahmoud attracts widespread praise for his work erasing the achievement gap. Attorney Michael Ciresi has donated $200,000 to Harvest Prep through his law firm's children's foundation.

"He's doing a fabulous job and the test scores are not a fluke," said Ciresi, who loaned the school another $750,000 after recent education funding shifts made it hard for charter schools to borrow money.

Few of Mahmoud's detractors are willing to publicly criticize his methods, but some say the school is so obsessed with the MCA tests, it might be shortchanging students in other areas. Some contend Mahmoud's school has fewer special education students and cherry-picks the brightest Minneapolis kids -- theories he discounts.

Michael Diedrich, an education policy analyst for the Minnesota 2020 think tank, acknowledges Harvest Prep's great test scores, but notes its students haven't performed well or improved on new science standards tests.

"They recognize that math and reading is what everyone cares about, so they focus on those areas and test well," Diedrich said. "But the data make me wonder if they're not preparing their students as well in other areas."

Said former Minneapolis Superintendent Peter Hutchinson: "We should all be careful as to whether this is the silver bullet, but these kids are learning like crazy. It's so structured that people in the education establishment worry that it's too restrictive and regimented. But here's the problem: It works."

On a typical day, Mahmoud is on his treadmill at 5 a.m. at his Brooklyn Park home. His job includes writing grants, tutoring kids and making sure the bells don't ring during MCAs.

He'll be inducted in to the Charter School Hall of Fame this summer, but says "there's a fine line between being famous and infamous.

"We work hard, but so do a lot of people," Mahmoud said. "The difference is we are blessed to see the fruits of our labors. Nothing beats tutoring a child when he or she gets that 'aha' moment and gets it. Instead of complaining about the problem, it feels great to do something about it."

The Wisconsin Assembly planned to finish its work for the year Thursday by approving $350 million to build a new prison and provide all parents a $100 per-child tax rebate, although it's uncertain whether either will pass the Senate.

A couple hundred Minneapolis students set out Wednesday afternoon on a march from Martin Luther King Jr. Park in south Minneapolis to City Hall to "voice our concerns about gun violence in schools," according to a Facebook post.